Audi P0173 Fuel System 2/1 Rich Control Over Limit

Description

OBD-II Trouble Code Description for P0173 Audi

Fuel Trim

What does this mean?

OBD2 Code P0173 Audi definition:
This code is one that surfaces with certain makes of automobiles more than others. In writing this article I’ve added Mercedes-Benz-specific info since it seems that M-B (and VW) are most prone to having this P0173 Audi surface along with misfire codes or other fuel trim codes. P0173 Audi means there was a malfunction in the computer’s control of the air:fuel ratio. It also indicates that the fuel trims reached their limit of adding fuel while trying to compensate for a actual or perceived rich condition. When the fuel trims reach their rich correction limit, the PCM (Powertrain Control Module) sets a P0173 Audi, indicating a problem or malfunction in the fuel trims. It may also have a P0170 Audi referring to the same malfunction but on bank one.

Symptoms

Possible sumptoms of OBD code P0173 Audi
MIL (Malfunction Indicator Lamp) Illumination Start and stall Poor fuel economy Black smoke at tailpipe Hesitation/misfire at idle or under load

Causes

Possible causes of OBD code P0173 Audi
Potential causes include a vacuum leak, unmetered air leaks Fuel saturated engine oil Leak in turbo air charge hoses (if equipped) Possibly bad O2 sensor (If Mercedes, may require adaptation with M-Benz compatible scan tool.) Oil contamination in MAF connector or O2 sensor connectors. Also check ignition coils, cam and crank sensors, and oil sensor for leakage contributing to oil intrusion in wiring harness. Defective MAF (Mass Air Flow) sensor (especially on Mercedez-Benz and other European autos. There are a lot of problems with aftermarket MAF sensors.) Defective fuel pressure regulator Leaking camshaft adjuster solenoids (Mercedes-Benz). NOTE: for some Mercedes-Benz models there is a service recall for a crankcase vent hose located under the intake manifold. It should be checked for leaks/cracking and also operation of check valve in the hose. The check valve should flow only one way.

Possible Solutions

It should be stated right off the bat that the most common problem associated with this code is the MAF sensor or air mass meter. This is especially the case with Mercedes-Benz and Volkswagen and other European cars. At time of writing, you don’t normally see this code with American-made cars, and minimally with Asian, and, to be honest, I have no idea why. It appears to me that the PCM (powertrain control module) logic used by some European car manufacturers to set a P0173 Audi (or P0173 Audi) fault code simply isn’t used by American vehicle manufacturers. It is more common to see P0171 Audi, 0174, 0172, 0175 codes set with regard to fuel trim malfunctions on American cars. There is very little information on the setting conditions for a P0173 Audi, or P0173 Audi, but what information that is available almost seems to be a redundancy of the P0171 Audi,4,2 & 5 setting conditions. I’m sure there’s a reason for it, but I can’t get anyone to tell me what that is. The similarities between them may be why we don’t see this code surface on domestic vehicles very often. It’s simply unnecessary. So, simply put, if you have a P0173 Audi, your PCM noticed that the fuel trims reached their rich correction limit. Basically it’s adding fuel to try to compensate for a lean condition, real or perceived. If you have this code and access to a scan tool, observe the MAF sensor reading in grams/sec. The reading will be different for different automobiles, so get a good spec. I’m going to stick with what would be normal for a Mercedes (1.8L), since they have the bulk of the trouble. Expect to see at idle 3.5-5 g/s (ideally). At 2500 RPMs with no load it should be between 9 and 12 g/s. On road test, at WOT (wide open throttle) it should be 90 g/s or well above. If it’s not in specs, replace it. Be careful of Ebay MAFs. Often they don’t work according to OE specifications. If the MAF checks out and there is no oil intrusion at the connector, check fuel pressure and ensure that there are no leaks at the regulator internally or externally. Check all vacuum hoses and confirm none are cracked, disconnected or missing. Make sure there are no vacuum leaks at the intake manifold gaskets or tears in the air supply hose. If the engine is turbo charged, be sure the hoses are in good condition and have no leaks. Leaking turbo pressure hoses could cause a rich condition. Inspect the condition of crankcase vent hose under intake manifold and operation of check valve in the hose. (In the “What are the causes?” section) If there doesn’t appear to be any problems with the fuel pressure, MAF or vacuum hoses, then inspect the O2 sensor connectors for oil intrusion. A bad O2 sensor could cause a P0170 Audi, or P0173 Audi. Repair cause of oil leak and replace oil-fouled O2 sensor. Article written by Dale Toalston

The OBD2 Code Information Be Applicable For Audi:

2013 Audi TT ultra quattro Concept,2013 Audi TT RS plus,2013 Audi TTS Roadster competition,2013 Audi TTS Coupe competition,2013 Audi Sport quattro Concept,2013 Audi SQ5 TDI,2013 Audi S8,2013 Audi S7 Sportback,2013 Audi S6 Avant,2013 Audi S6,2013 Audi S4 Avant,2013 Audi S4,2013 Audi RS5 DTM,2013 Audi RS4 Avant,2013 Audi R8 e-tron Concept,2013 Audi R8 V10 plus,2013 Audi R8 V10 Spyder,2013 Audi R8 V10,2013 Audi R8,2013 Audi Q5,2013 Audi Nanuk quattro Concept,2013 Audi A8 L Hybrid,2013 Audi A8 Hybrid,2013 Audi A6 allroad quattro,2013 Audi A6 Black Edition,2013 Audi A4 allroad quattro,2013 Audi A4 Avant,2013 Audi A4,2013 Audi A3 e-tron Concept,2013 Audi A3,2013 Audi A1 quattro,2012 Audi e-bike Worthersee Concept,2012 Audi S5 Sportback,2012 Audi S5 Cabriolet,2012 Audi S5,2012 Audi RS Q3 Concept,2012 Audi RS5,2012 Audi RS3 Sportback,2012 Audi R8 GT Spyder,2012 Audi R8 Exclusive Selection,2012 Audi Q5 Hybrid quattro,2012 Audi Q3 Vail Concept,2012 Audi Q3 Jinlong Yufeng Concept,2012 Audi Q3,2012 Audi Crosslane Coupe Concept,2012 Audi A8 L Security,2012 Audi A6 L e-tron Concept,2012 Audi A6 Hybrid,2012 Audi A6 Avant,2012 Audi A6,2012 Audi A5 Sportback,2012 Audi A5 DTM,2012 Audi A5 Coupe,2012 Audi A5 Cabriolet,2012 Audi A1 amplified,2012 Audi A1 Sportback,2011 Audi Urban Spyder Concept,2011 Audi Urban Concept,2011 Audi TT Roadster,2011 Audi TT Coupe,2011 Audi TTS Roadster,2011 Audi TTS Coupe,2011 Audi S5 Sportback,2011 Audi RS5,2011 Audi R8 Spyder 5.2 FSI quattro,2011 Audi R8 Spyder 4.2 FSI quattro,2011 Audi R8 GT,2011 Audi R18,2011 Audi Q7,2011 Audi A8 L,2011 Audi A8,2011 Audi A7 Sportback,2011 Audi A3 e-tron Concept,2011 Audi A3 Sportback,2011 Audi A3 Concept,2011 Audi A3 Cabriolet,2011 Audi A3,2011 Audi A2 Concept,2011 Audi A1 clubsport quattro Concept,2011 Audi A1,2010 Audi quattro Concept,2010 Audi e-tron Spyder Concept,2010 Audi e-tron Concept,2010 Audi TT RS Roadster,2010 Audi TT RS,2010 Audi TT GT4 Concept,2010 Audi S5 Cabriolet,2010 Audi R8 V10 5.2 FSI quattro,2010 Audi Q7,2010 Audi A8 Hybrid Concept,2010 Audi A5 Sportback,2010 Audi A5 Cabriolet,2010 Audi A4 allroad quattro,2010 Audi A1 e-tron Concept,2009 Audi e-tron Concept,2009 Audi TTS Roadster,2009 Audi TTS Coupe,2009 Audi Sportback Concept,2009 Audi S6 Avant,2009 Audi S6,2009 Audi S4 Avant,2009 Audi S4,2009 Audi S3 Sportback,2009 Audi S3,2009 Audi RS6,2009 Audi R8 GT3,2009 Audi Q7 V12 TDI,2009 Audi Q5 Custom Concept,2009 Audi Q5,2009 Audi A6 allroad quattro,2009 Audi A6 Avant,2009 Audi A6,2009 Audi A4 Avant,2009 Audi A4,2009 Audi A3 Sportback,2009 Audi A3,2008 Audi TT clubsport quattro Concept,2008 Audi TT Roadster 3.2 quattro,2008 Audi TT Coupe,2008 Audi S8,2008 Audi S6,2008 Audi S5,2008 Audi S4 Cabriolet,2008 Audi RS6 Avant UK Version,2008 Audi RS6 Avant,2008 Audi RS4 Cabriolet,2008 Audi RS4,2008 Audi R8 V12 TDI Concept,2008 Audi R8 TDI Le Mans Concept,2008 Audi R8,2008 Audi Q7,2008 Audi A8 L,2008 Audi A8 4.2 TDI quattro,2008 Audi A8L W12 quattro,2008 Audi A8,2008 Audi A6 Avant,2008 Audi A6,2008 Audi A5 3.0 TDI quattro,2008 Audi A5,2008 Audi A4 US Version,2008 Audi A4 TDI Concept e,2008 Audi A4 Cabriolet,2008 Audi A4,2008 Audi A3 US Version,2008 Audi A3 TDI clubsport quattro Concept,2008 Audi A3 Cabriolet,2008 Audi A1 Sportback Concept,2007 Audi metroproject quattro Concept,2007 Audi TT clubsport quattro Concept,2007 Audi TT Roadster 2.0 TFSI,2007 Audi TT Roadster,2007 Audi TT Coupe S-line,2007 Audi TT Coupe,2007 Audi S3,2007 Audi R8,2007 Audi Q7 V12 TDI Concept,2007 Audi Q7 V12 TDI,2007 Audi Cross Coupe quattro Concept,2007 Audi Cross Cabriolet quattro Concept,2006 Audi S8,2006 Audi S6 Avant,2006 Audi S6,2006 Audi S4 Cabriolet,2006 Audi Roadjet Concept,2006 Audi RS 4 Cabriolet,2006 Audi RS 4 Avant,2006 Audi RS4,2006 Audi Q7,2006 Audi A8 Security,2006 Audi A6 allroad quattro,2006 Audi A4 Cabriolet,2006 Audi A3 2.0T,2005 Audi allroad quattro V8 4.2,2005 Audi allroad quattro V6 2.7T,2005 Audi TT quattro sport,2005 Audi TT Roadster 3.2,2005 Audi TT Roadster 1.8T,2005 Audi TT Coupe 3.2,2005 Audi TT Coupe 1.8T,2005 Audi Shooting Brake Concept,2005 Audi S4 Cabriolet,2005 Audi S4 Avant,2005 Audi S4,2005 Audi RS4,2005 Audi Q7 Hybrid Concept,2005 Audi Allroad quattro Concept,2005 Audi A8 L W12,2005 Audi A8 L 4.2,2005 Audi A8 4.2 TDI quattro,2005 Audi A8 4.2,2005 Audi A8 3.2 FSI quattro,2005 Audi A8L 4.2 TDI quattro,2005 Audi A6 Avant,2005 Audi A6 4.2 quattro Sline,2005 Audi A6 3.2,2005 Audi A6 3.0 TDI quattro,2005 Audi A6L,2005 Audi A4 DTM Edition,2005 Audi A4 Cabriolet,2005 Audi A4 Avant 3.2 quattro,2005 Audi A4 3.2 quattro,2005 Audi A4 3.0 TDI quattro,2005 Audi A4 2.0T,2005 Audi A3 2.0 TDI 3-door,2004 Audi S4 Cabriolet,2004 Audi RSQ Concept,2004 Audi RS6 plus,2004 Audi A8 L 6.0 W12 quattro,2004 Audi A8 L 3.0 quattro,2004 Audi A8 4.2 quattro,2004 Audi A8 3.7 quattro,2004 Audi A8 3.0 TDI quattro,2004 Audi A8,2004 Audi A3 Sportback quattro,2004 Audi A3 Sportback S-line,2004 Audi A3 Sportback,2004 Audi A3 3-door,2003 Audi allroad quattro,2003 Audi TT Roadster 3.2 quattro,2003 Audi TT 3.2 DSG quattro,2003 Audi Pikes Peake quattro Concept,2003 Audi Nuvolari quattro Concept,2003 Audi Le Mans quattro Concept,2003 Audi A8 L 4.2 quattro,2003 Audi A8 4.0 TDI quattro,2003 Audi A4,2003 Audi A3 3.2 V6 3-door,2003 Audi A3 3-door,2003 Audi A2,2002 Audi allroad quattro 4.2,2002 Audi allroad quattro,2002 Audi TT Roadster,2002 Audi S6 Avant,2002 Audi S6,2002 Audi S4 Avant,2002 Audi S4,2002 Audi S3,2002 Audi RS6 Sedan,2002 Audi RS6 Avant,2002 Audi RS6,2002 Audi A6,2002 Audi A4 Cabriolet 3.0,2002 Audi A4 Cabriolet 2.4,2002 Audi A4 Cabriolet 1.8 T,2002 Audi A4 Cabriolet,2002 Audi A4 Avant,2002 Audi A4,2002 Audi A3 3-door,2002 Audi A2,2001 Audi TT Coupe,2001 Audi Avantissimo Concept,2001 Audi A8 L 6.0 quattro,2001 Audi A6 Avant,2001 Audi A6,2001 Audi A4 Avant,2001 Audi A4

 

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